Effects of three Hb-based oxygen-carrying solutions on neutrophil activation in vitro: quantitative measurement of the expression of adherence receptors

BACKGROUND: Hb-based oxygen carriers (HbOCs) are currently under investigat ion as RBC substitutes. These solutions have vasoactive properties and may modify the behavior of the RBC in vitro. The effects of these agents on oth er blood cells have not been extensively investigated. The aim of this stud y was to evaluate the potential effect(s) of three differently modified HbO Cs on the activation of PMNs. STUDY DESIGN AND METHODS: Whole blood from humans was incubated with Hb dex tran-benzenetetracarboxylate, aa-Hb, or o-raffinose-poly-Hb for 15, 30, and 60 minutes. The expression of adherence receptors CD62L, CD18, and CD11b, which reflects the activation state of the neutrophils, was assessed in vit ro by a direct immunofluorescence method using calibration beads measured b y flow cytometry. RESULTS: The observed expression of each of the three adherence receptors f or each solution at each time point was similar to that noted with the RPMI control. Decreases in CD62L and increases in CD18 expression were noted at 15 minutes of incubation but, when those values were compared to the value s obtained with TNF alpha as the positive control of PMN activation, the pr ofile of expression of adherence receptors obtained with HbOC solutions did not conform to the expected activation profile of PMNs. CONCLUSION: Hb solutions modified by a variety of methods, as obtained and employed in this study, did not appear to activate neutrophils in vitro.